feat(database): shape the library like files, and shrink the catalog

Plans 013 and 014, the album page that prompted them, and the smaller
fixes they turned up. Changelog, largest first.

## The local library is shaped like files, not like MusicBrainz

`audio_files` carries its own tags and points at `albums` and
`artists`; `file_genres` is the one real many-to-many. `recordings`,
`release_group_recordings`, `artist_credit`, `artist_credit_artist`,
`recording_genres`, `release_groups` and `release_to_rg` are gone from
the local side, and with them a six-way join in every read, a
`MIN(release_group_id)` subquery in eleven queries and a
first-credited-artist subquery in nine. Measured on a real 25,966-file
library, every many-to-many that model expressed was 1:1 in the data.

- Ownership is a file. `GetFilePathsByRecordingMBIDs`,
  `LibraryMBIDIndex.CheckMBIDs`, `collectLibraryEntities` and
  `pruneStaleLocalCrossReferences` all join `audio_files`, so the 812
  orphaned recordings, 216 release groups and 260 artists that library
  carried are now structurally impossible.
- One projection: every track query selects from the `track_metadata`
  view, one row type, one mapper. Nine hand-rolled copies had drifted
  far enough to report different years on different screens.
- `library_id = 0` means every library, so each list query exists once
  instead of scoped and unscoped with a branch at every call site.
- No migration chain. `sql/schemas/` is the one description of the
  shape; `sql/migrations/`, `applyMigrations` and `schema_migrations`
  are squashed away, along with the drift between them that had sqlc
  generating against a stale schema.
- `database.InsertTestTrack` is the one test seeder; twenty test files
  had been assembling the old FK chain each in its own order.

## The catalog stores its ids as bytes

`explore_index`'s three 36-char MBID columns and its entity-type text
are 16 raw bytes and a small integer. The table and its six indexes go
780 MB to 405 MB on a real 2,052,200-row catalog, which is why a fresh
install is ~0.6 GB rather than ~1.0 GB.

- `backend/explore/mbid.go` is the only place the encoding is known;
  everything above it speaks dashed strings.
- `CHECK(length(mbid) = 16)` makes a stringly write fail at the insert
  rather than silently returning no rows, since SQLite does not coerce
  between TEXT and BLOB.
- The importer asks the artifact what encoding it carries and converts
  on the way in, so the artifact already published keeps working and no
  format bump is needed.
- `indexRowColumns`/`scanIndexRow` replace four copies of a 22-column
  list, and `TestStoredEncodingRoundTrips` sweeps every read path.

## An album page that says how much of the album is yours

- One question, asked once: is there a file. `filePaths` is filled by a
  single batched lookup when the tracklist settles, and the badge, the
  Play count, the dimmed rows and every menu item read it — replacing
  four claims of decreasing confidence that could show a green tick on
  an album whose every action did nothing.
- Play, Play 7 of 12, or no play button at all.
- `total_tracks` on `explore_index` (~2 bytes over 400,677 release
  groups) and on `audio_files` from tags that have always carried it:
  a complete MBID-matched album now makes no catalog call at all, where
  it used to spend the most expensive request the app makes.
- A merged cluster shows the running order the most releases agree on,
  and the version list marks the release you own rather than standing a
  synthetic entry in for it.
- `AlbumReleasesFailed`: a slow fetch is no longer reported as a failed
  one by a 12-second timer.
- Rows not in the library are dimmed in place (with `aria-disabled`)
  instead of the owned ones wearing a green tick and a legend.

## Caches and cover art get ceilings

- Only the three tiers of a cover are stored; the full-resolution copy
  nothing rendered was 1,134 MB of a 1.4 GB covers directory.
- One artist portrait is downloaded and the rest are remembered as
  URLs — 4.1 GB of a 5.3 GB cache was candidates no code path reads.
- `browsedArtBudget` and `httpCacheBudget` bound what an age cannot:
  the same install held art for 5,770 artists in a 1,301-artist
  library.
- `OrphanedArtistImagesJob` joined a bare MBID onto a sharded
  directory, so it deleted the rows that were the only record of the
  files it left behind. `explore.ArtistImageDir` is that layout's one
  definition now.

## The autotag queue asks whether there is work

`tagging_items` was a row per album folder, not a queue, and no query
read the `tag_status` column that held the answer. The four queue
queries ask the files, which matters most where it is least visible:
`startPrefetch` was scoring every album in a tagged library against
MusicBrainz.

## Phantom playlist tracks resolve in place

An M3U8 imported before its files leaves phantom rows; they now match
by path and fall back to position, keep their place in the playlist
when resolved, and pair best-first so two phantoms cannot claim the
same file.

## Playing a track plays the list it is in

Double-click, and Play on a single row's menu, queue the list as
displayed with `startIndex` on that row — the album page and the track
list used to queue one track and discard the album around it. A
multi-row selection still plays exactly itself.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AfVYUVExXsx1nSWrXN8mAh

backend/database/lyrics_search_test.go

@@ -4,59 +4,33 @@ import (
 	"testing"
 )
 
-// seedLyricsTrack inserts the minimal FK chain (artist_credit →
-// recording → audio_file → release_group link) for one track with the
-// given lyrics, so lyric-search tests have realistic joins.
+// seedLyricsTrack inserts one file with the given lyrics, so lyric
+// searches have something realistic to join against.  It used to
+// insert a four-row FK chain by hand.
 func seedLyricsTrack(
 	t *testing.T,
 	db *DB,
 	id int64,
 	title, artist, album, lyrics string,
 	lenMs int64,
-) {
+) int64 {
 	t.Helper()
 
-	if _, err := db.ExecContext(
-		"INSERT OR IGNORE INTO artist_credit (id, text) VALUES (?, ?)", id, artist,
-	); err != nil {
-		t.Fatalf("insert artist_credit: %v", err)
+	fileID := InsertTestTrack(t, db, TestTrack{
+		FilePath: "/music/track" + itoa(id) + ".mp3",
+		Title:    title,
+		Artist:   artist,
+		Album:    album,
+		LengthMs: lenMs,
+	})
+
+	if lyrics != "" {
+		if err := db.SetLyrics(fileID, lyrics, "tag", ""); err != nil {
+			t.Fatalf("seed lyrics: %v", err)
+		}
 	}
 
-	if _, err := db.ExecContext(
-		"INSERT OR IGNORE INTO release_groups (id, name) VALUES (?, ?)", id, album,
-	); err != nil {
-		t.Fatalf("insert release_group: %v", err)
-	}
-
-	if _, err := db.ExecContext(
-		"INSERT INTO recordings (id, name, artist_credit_id, lyrics) VALUES (?, ?, ?, ?)",
-		id, title, id, nullableLyrics(lyrics),
-	); err != nil {
-		t.Fatalf("insert recording: %v", err)
-	}
-
-	if _, err := db.ExecContext(
-		"INSERT INTO audio_files (id, file_path, length_milliseconds, file_type_id, recording_id) "+
-			"VALUES (?, ?, ?, ?, ?)",
-		id, "/music/track"+itoa(id)+".mp3", lenMs, 0, id,
-	); err != nil {
-		t.Fatalf("insert audio_file: %v", err)
-	}
-
-	if _, err := db.ExecContext(
-		"INSERT INTO release_group_recordings (release_group_id, recording_id) VALUES (?, ?)",
-		id, id,
-	); err != nil {
-		t.Fatalf("insert release_group_recordings: %v", err)
-	}
-}
-
-func nullableLyrics(l string) any {
-	if l == "" {
-		return nil
-	}
-
-	return l
+	return fileID
 }
 
 func itoa(v int64) string {
@@ -111,8 +85,8 @@ func TestSearchLyrics(t *testing.T) {
 		}
 
 		h := hits[0]
-		if h.RecordingID != 1 {
-			t.Errorf("RecordingID = %d, want 1", h.RecordingID)
+		if h.AudioFileID != 1 {
+			t.Errorf("RecordingID = %d, want 1", h.AudioFileID)
 		}
 
 		if h.Title != "The Sound of Silence" {
@@ -191,11 +165,11 @@ func TestSetRecordingLyricsUpdatesIndex(t *testing.T) {
 
 	// Backfill lyrics — should update both the column and the FTS index.
 	const lyrics = "Yesterday all my troubles seemed so far away"
-	if err := db.SetRecordingLyrics(1, lyrics); err != nil {
+	if err := db.SetLyrics(1, lyrics, "lrclib", ""); err != nil {
 		t.Fatalf("SetRecordingLyrics: %v", err)
 	}
 
-	stored, err := db.GetRecordingLyrics(1)
+	stored, err := db.GetLyrics(1)
 	if err != nil {
 		t.Fatalf("GetRecordingLyrics: %v", err)
 	}
@@ -209,7 +183,7 @@ func TestSetRecordingLyricsUpdatesIndex(t *testing.T) {
 		t.Fatalf("SearchLyrics: %v", err)
 	}
 
-	if len(hits) != 1 || hits[0].RecordingID != 1 {
+	if len(hits) != 1 || hits[0].AudioFileID != 1 {
 		t.Fatalf("expected recording 1 after backfill, got %+v", hits)
 	}
 }
@@ -222,7 +196,7 @@ func TestRecordingsMissingLyrics(t *testing.T) {
 	seedLyricsTrack(t, db, 1, "Has Lyrics", "Artist A", "Album A", "some words here", 100000)
 	seedLyricsTrack(t, db, 2, "No Lyrics", "Artist B", "Album B", "", 200000)
 
-	missing, err := db.RecordingsMissingLyrics(50)
+	missing, err := db.FilesMissingLyrics(50)
 	if err != nil {
 		t.Fatalf("RecordingsMissingLyrics: %v", err)
 	}
@@ -232,7 +206,7 @@ func TestRecordingsMissingLyrics(t *testing.T) {
 	}
 
 	c := missing[0]
-	if c.RecordingID != 2 || c.Title != "No Lyrics" || c.Artist != "Artist B" {
+	if c.AudioFileID != 2 || c.Title != "No Lyrics" || c.Artist != "Artist B" {
 		t.Errorf("unexpected candidate: %+v", c)
 	}
 
@@ -241,7 +215,7 @@ func TestRecordingsMissingLyrics(t *testing.T) {
 	}
 
 	// Single-recording lookup mirrors the batch fields.
-	one, err := db.RecordingLyricLookup(2)
+	one, err := db.FileLyricLookup(2)
 	if err != nil {
 		t.Fatalf("RecordingLyricLookup: %v", err)
 	}